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GLASS CERAMIC WITH QUARTZ SOLID SOLUTION PHASES

20240132396 ยท 2024-04-25

    Inventors

    Cpc classification

    International classification

    Abstract

    Quartz solid solution glass ceramics and precursors thereof are described. which are characterized by very good mechanical and optical properties and can be used in particular as restorative materials in dentistry.

    Claims

    1. A glass ceramic, which comprises the following components TABLE-US-00012 Component Wt.-% SiO.sub.2 68.0 to 81.0 Li.sub.2O 6.0 to 14.0 Al.sub.2O.sub.3 1.0 to 8.0 and comprises at least two different quartz solid solution phases.

    2. The glass ceramic according to claim 1, which comprises at least one non-stoichiometric quartz solid solution phase(s).

    3. The glass ceramic according to claim 1, which comprises at least one stoichiometric or non-stoichiometric aluminosilicate crystal phase(s).

    4. The glass ceramic according to claim 1, which comprises at least two different quartz solid solution phases whose highest intensity reflection peaks in X-ray powder diffraction with Cu.sub.K? radiation are each in the range of 25 to 26.7? 2?.

    5. The glass ceramic according to claim 1, which comprises two different quartz solid solution phases whose highest-intensity reflection peaks in X-ray powder diffraction with Cu.sub.K? radiation have a spacing of at least 0.2? 2?.

    6. The glass ceramic according to claim 1, which comprises 70.0 to 79.0 wt.-% SiO.sub.2.

    7. The glass ceramic according to claim 1, which comprises 7.5 to 13.0 wt.-% Li.sub.2O.

    8. The glass ceramic according to claim 1, which comprises 2.0 to 6.5 wt.-% Al.sub.2O.sub.3.

    9. The glass ceramic according to claim 1, which comprises 1.0 to 7.0 wt.-% P.sub.2O.sub.5.

    10. The glass ceramic according to claim 1, which comprises 1.0 to 8.0 wt.-% oxide of monovalent elements Me.sup.I.sub.2O selected from the group of K.sub.2O, Na.sub.2O, Rb.sub.2O, Cs.sub.2O and mixtures thereof.

    11. The glass ceramic according to claim 1, which comprises 0 to 5.0 wt.-% K.sub.2O.

    12. The glass ceramic according to claim 1, which comprises 0 to 9.0 wt.-% oxide of divalent elements Me.sup.IIO selected from the group of Cao, MgO, SrO, ZnO and mixtures thereof.

    13. The glass ceramic according to claim 1, which comprises 0 to 6.0 wt.-% MgO.

    14. The glass ceramic according to claim 1, which comprises 0 to 5.0 wt.-% oxide of trivalent elements Me.sup.III.sub.2O.sub.3 selected from the group of B.sub.2O.sub.3, Y.sub.2O.sub.3, La.sub.2O.sub.3, Ga.sub.2O.sub.3, In.sub.2O.sub.3 and mixtures thereof.

    15. The glass ceramic according to claim 1, which comprises SiO.sub.2 and Li.sub.2O in a molar ratio in the range of 2.2 to 6.0.

    16. The glass ceramic according to claim 1, which comprises lithium disilicate or lithium metasilicate as main crystal phase.

    17. The glass ceramic according to claim 1, which comprises at least 20 wt.-% lithium disilicate crystals.

    18. The glass ceramic according to claim 1, which comprises 0.2 to 28 wt.-% quartz solid solution phases.

    19. A starting glass comprising the components of the glass-ceramic according to claim 1.

    20. The starting glass according to claim 19, which comprises nuclei for the crystallization of two different quartz solid solution phases and also nuclei for the crystallization of lithium disilicate or lithium metasilicate.

    21. The glass ceramic according to claim 1, wherein the glass ceramic is in the form of a powder, a granulate, a blank or a dental restoration.

    22. A process for producing the glass ceramic according to claim 1 in which a starting glass in particulate form is subjected to at least one heat treatment in the range from 800 to 1000? C.

    23. (canceled)

    24. (canceled)

    25. A process of producing a dental restoration selected from a bridge, inlay, onlay, veneer, abutment, partial crown, crown or facet, in which the glass ceramic according to claim 1 is given the shape of the desired dental restoration by pressing or machining.

    Description

    EXAMPLES

    Examples 1 to 24Composition and Crystal Phases

    [0080] A total of 24 glasses and glass ceramics according to the invention with the composition indicated in Table I were produced by melting of corresponding starting glasses and subsequent heat treatment for controlled crystallization.

    [0081] The heat treatments applied are also given in Table I. The following meanings apply

    TABLE-US-00010 T.sub.g Glass transition temperature, determined by DSC T.sub.S and t.sub.S Applied temperature and time for melting of the starting glass T.sub.Kb and t.sub.Kb Applied temperature and time for nucleation of the starting glass T.sub.C and t.sub.C Applied temperature and time for crystallization T.sub.Sinter and t.sub.Sinter Applied temperature and time for the sintering T.sub.Press and t.sub.Press Applied temperature and time for crystallization by hot pressing CR value Contrast value of glass ceramic determined according to British Standard BS 5612 using: Instrument: Spectrometer CM-3700d (Konica- Minolta) Measurement parameters: Measuring surface: 7 mm ? 5 mm Measurement type: Remission/Reflection Measuring range: 400 nm-700 nm Sample size: Diameter: 15-20 mm Thickness: 2 mm +/? 0.025 mm Plane parallelism: +/?0.05 mm Surface roughness: about 18 ?m. CTE Coefficient of thermal expansion of the glass ceramic according to ISO 6872 (2008), measured in the range from 100 to 500? C. ?.sub.Biax Biaxial fracture strength, measured according to dental standard ISO 6872 (2008)

    [0082] For this purpose, the starting glasses were first melted from usual raw materials in a platinum-rhodium crucible at the temperature T.sub.S for a duration t.sub.S in air atmosphere.

    [0083] In the examples 1 to 23 glass frits, i.e. glass granules, were produced by pouring the melted starting glasses into water. The glass frits were ground to a particle size of <45 ?m using ball or mortar mills and pressed into powder compacts using powder presses.

    [0084] The powder compacts were sintered, optionally after heat treatment at the temperature T.sub.Kb for a duration t.sub.Kb for nucleation, at temperature T.sub.Sinter for a duration t.sub.Sinter to dense bodies, during which nucleation and crystallization processes occurred simultaneously.

    [0085] The sintered blanks thus obtained were optionally subsequently shaped by hot pressing at temperature T.sub.Press for a duration t.sub.Press.

    [0086] In example 24 the melt of the starting glass was cast into a graphite mould to produced glass monoliths. These glass monoliths were directly after casting subjected to a first heat treatment at a temperature TK for a duration of t.sub.Kb to form nuclei and then slowly cooled to room temperature. Subsequently they were subjected to a heat treatment at a temperature T.sub.C for a duration of t.sub.C to effect crystallisation.

    [0087] In the following table I means:

    TABLE-US-00011 TABLE I Example 1 2 3 4 5 Composition Wt.-% Wt.-% Wt.-% Wt.-% Wt.-% SiO.sub.2 72.5 70.3 74.1 74.7 76.0 Li.sub.2O 11.6 11.3 11.1 10.1 9.6 K.sub.2O 1.7 1.7 1.7 1.8 1.7 MgO 4.4 4.3 2.9 3.6 2.8 SrO 2.8 SnO 0.1 Al.sub.2O.sub.3 2.8 5.5 2.8 3.6 4.5 Yb.sub.2O.sub.3 1.4 Gd.sub.2O.sub.3 1.3 Eu.sub.2O.sub.3 0.3 ZrO.sub.2 0.9 GeO.sub.2 1.0 Ta.sub.2O.sub.5 3.2 3.1 P.sub.2O.sub.5 3.8 3.8 3.7 3.8 3.7 T.sub.g [? C.] 469 457 461 471 T.sub.s [? C.] 1500 1550 1550 1550 t.sub.s [min] 60 60 60 60 T.sub.Sinter [? C.] 890 860 890 890 900 t.sub.Sinter [min] 10 10 10 10 10 T.sub.press [? C.] 870 t.sub.press [min] 25 Crystal phases Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 QMK1 QMK1 QMK1 QMK1 QMK1 QMK2 QMK2:LAS QMK2 QMK2 QMK2 Strongest peak of QMK1 [?2?] 26.0 25.9 26.0 26.0 26.0 Strongest peak of QMK2 [?2?] 26.5 26.3 26.5 26.4 26.4 ?.sub.Biax [MPa] CR value 71.25 46.16 L* 90.81 92.08 a* ?0.11 ?0.72 b* 6.22 5.82 WAK.sub.100-500? C. [10.sup.?6K.sup.?1] 12.89 13.46 Example 6 7 8 9 10 Composition Wt.-% Wt.-% Wt.-% Wt.-% Wt.-% SiO.sub.2 74.5 74.0 74.0 74.1 74.6 Li.sub.2O 11.6 11.9 11.5 11.2 10.6 K.sub.2O 1.9 1.7 1.7 1.7 1.7 MgO 3.3 4.5 3.6 3.5 3.5 Al.sub.2O.sub.3 3.7 3.4 3.7 3.6 3.7 B.sub.2O.sub.3 1.3 Nd.sub.2O.sub.3 2.1 Bi.sub.2O.sub.3 1.7 Pr.sub.2O.sub.3 0.6 CeO.sub.2 0.1 GeO.sub.2 1.0 MnO.sub.2 0.8 P.sub.2O.sub.5 3.8 3.9 3.8 3.8 3.8 AgCl 0.03 AgBr 0.03 AgI 0.04 T.sub.g [? C.] 464 469 461 467 461 T.sub.s [? C.] 1550 1550 1550 1550 1550 t.sub.s [min] 60 60 60 60 60 T.sub.Sinter [? C.] 890 890 890 890 890 t.sub.Sinter [min] 10 10 10 10 10 Crystal phases Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 QMK1 QMK1 QMK1 QMK1 QMK1 QMK2 QMK2 QMK2 QMK2 QMK2 Strongest peak of QMK1 [?2?] 26.0 26.0 26.0 26.0 26.0 Strongest peak of QMK2 [?2?] 26.4 26.4 26.5 26.4 26.4 ?.sub.Biax [MPa] CR value L* a* b* WAK.sub.100-500? C. [10.sup.?6K.sup.?1] Example 11 12 13 14 15 Composition Wt.-% Wt.-% Wt.-% Wt.-% Wt.-% SiO.sub.2 72.5 78.7 77.3 71.7 71.7 Li.sub.2O 11.6 8.7 7.7 10.2 12.7 K.sub.2O 1.7 1.6 1.7 3.4 Rb.sub.2O 3.3 MgO 3.6 2.8 2.8 2.8 3.7 CaO 2.0 Al.sub.2O.sub.3 4.0 4.5 5.2 6.0 4.1 La.sub.2O.sub.3 1.2 Er.sub.2O.sub.3 2.6 TiO.sub.2 0.6 CeO.sub.2 1.2 V.sub.2O.sub.5 0.3 P.sub.2O.sub.5 3.8 3.0 2.8 4.1 4.4 T.sub.g [? C.] 471 473 510 477 471 T.sub.s [? C.] 1600 1600 1600 1600 1450 t.sub.s [min] 60 60 60 60 120 T.sub.Sinter [? C.] 890 890 890 890 870 t.sub.Sinter [min] 10 10 10 10 10 Crystal phases Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 QMK1 QMK1 QMK1 QMK1 QMK1 QMK2 QMK2 QMK2 QMK2:LAS QMK2 Strongest peak of QMK1 [?2?] 26.0 26.0 25.9 25.9 26.5 Strongest peak of QMK2 [?2?] 26.4 26.4 26.2 26.2 26.2 ?.sub.Biax [MPa] 363 CR value 57.38 89.17 92.41 L* 92.06 94.81 91.13 a* ?0.59 ?0.36 10.16 b* 6.05 2.5 ?2.15 WAK.sub.100-500? C. [10.sup.?6K.sup.?1] 13.76 Example 16 17 18 19 20 Composition Wt.-% Wt.-% Wt.-% Wt.-% Wt.-% SiO.sub.2 73.4 73.2 77.2 74.3 73.5 Li.sub.2O 11.8 10.7 10.6 11.9 11.8 Na.sub.2O 1.7 1.5 0.4 K.sub.2O 1.7 0.9 Rb.sub.2O 4.0 1.7 2.6 MgO 2.9 3.0 3.6 3.3 CaO 1.0 0.3 SrO 3.7 1.0 0.9 ZnO 0.7 Al.sub.2O.sub.3 2.7 4.6 2.8 2.8 3.7 P.sub.2O.sub.5 3.8 3.8 3.9 3.8 3.8 MoO.sub.3 0.5 WO.sub.3 0.5 T.sub.g [? C.] 457 468 458 458 463 T.sub.s [? C.] 1500 1550 1550 1550 1550 t.sub.s [min] 60 60 60 60 60 T.sub.Sinter [? C.] 900 890 890 890 890 t.sub.Sinter [min] 30 10 10 10 10 Crystal phases Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 QMK1 QMK1 QMK1 QMK1 QMK1 QMK2 QMK2 QMK2 QMK2 QMK2 Strongest peak of QMK1 [?2?] 26.1 26.0 26.0 26.0 26.0 Strongest peak of QMK2 [?2?] 26.6 26.3 26.5 26.5 26.4 ?.sub.Biax [MPa] CR value L* a* b* WAK.sub.100-500? C. [10.sup.?6K.sup.?1] Example 21 22 23 24 Composition Wt.-% Wt.-% Wt.-% Wt.-% SiO.sub.2 77.3 71.7 81.0 75.0 Li.sub.2O 9.1 12.7 6.4 12.0 Na.sub.2O 0.4 K.sub.2O 0.5 3.4 1.7 1.7 Rb.sub.2O 1.0 MgO 2.7 3.7 2.8 4.5 SrO ZnO 0.7 Al.sub.2O.sub.3 3.6 4.1 4.5 2.8 ZrO.sub.2 1.0 TiO.sub.2 0.7 0.6 P.sub.2O.sub.5 3.0 4.4 3.0 4.0 T.sub.g [? C.] 479 471 563 468 T.sub.s [? C.] 1550 1450 1600 1550 t.sub.s [min] 60 120 120 60 T.sub.Kb [? C.] 490 490 t.sub.Kb [min] 10 20 T.sub.C [? C.] 900 t.sub.C [min] 30 T.sub.Sinter [? C.] 890 870 980 t.sub.Sinter [min] 10 10 10 T.sub.press [? C.] 890 t.sub.press [min] 25 Crystal phases Li.sub.2Si.sub.2O.sub.5 Li.sub.2Si.sub.2O.sub.5 QMK1 QMK1 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 QMK2 QMK2 QMK1 QMK1 Li.sub.3PO.sub.4 Li.sub.3PO.sub.4 QMK2 QMK2 Li.sub.2SiO.sub.3 Li.sub.2Si.sub.2O.sub.5 Strongest peak of QMK1 [?2?] 25.9 26.5 26.1 26.0 Strongest peak of QMK2 [?2?] 26.4 26.2 26.5 26.5 ?.sub.Biax [MPa] CR value 81.5 L* 90.18 a* 0.25 b* 5.4 WAK.sub.100-500? C. [10.sup.?6K.sup.?1] QMK: Quartz solid solution phase QMK1: 1. quartz solid solution phase QMK2: 2. quartz solid solution phase LAS: Lithium aluminosilicate (Li.sub.2OAl.sub.2O.sub.37.5SiO.sub.2)

    [0088] The X-ray diffraction pattern resulting by X-ray diffraction of the glass ceramic obtained in Example 19 with CuK? radiation at room temperature is shown in FIG. 1. Below this X-ray diffraction pattern, the characteristic peaks (peak patterns) of the following crystal phases from the PDF-4+ 2020 database (International Centre for Diffraction Data) are reproduced and marked with the letters A to D: [0089] A: Low quartz (?-SiO.sub.2) [0090] B: High quartz (?-SiO.sub.2) [0091] C: Lithium disilicate (Li.sub.2Si.sub.2O.sub.5) [0092] D: Lithium phosphate (Li.sub.3PO.sub.4)

    [0093] In the X-ray diffraction pattern, two quartz solid solution phases are identifiable whose peak patterns are shifted toward smaller 2? values compared to the peak pattern of low quartz and whose highest intensity peaks are at 26.5? 2? and at 26.0? 2?, respectively.